Active matrix substrate and liquid crystal display device

An active matrix substrate includes a first pixel region defined by first and second source bus lines adjacent to each other and first and second gate bus lines adjacent to each other and further includes a first pixel electrode and a first oxide semiconductor TFT that are associated with the first pixel region. The first oxide semiconductor TFT includes an oxide semiconductor layer and a gate electrode electrically connected to the first gate bus line. The oxide semiconductor layer includes a channel region and a low-resistance region including first and second regions located on opposite sides of the channel region. When viewed in a direction normal to the substrate, the low-resistance region extends across the first source bus line to another pixel region and partially overlaps a pixel electrode disposed in the other pixel region with an insulating layer interposed therebetween.